Re: MOT power supply

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>



>I'm tempted to ask tranformer engineer friend how much it would cost to make
>power transformers built to the actual requirements of tesla coil builders
>(large power levels, and ability to take high peak voltages without failing,
>and something not huge and really heavy.)

Ken's raised all the significant points here.  Interestingly, companies 
that do make small runs of HV transformers (i.e. Peter Dahl, for example) 
will be happy to make you a semi custom transformer.  It will be expensive, 
though, compared to a used/reconditioned pole transformer, and cheap 
compared to a new pole transformer.  You're paying the difference for the 
overhead of a production run of 1 unit.

I'm sure if you were to invest in a production run of 100 transformers, you 
could probably get a real nice TC transformer at a real nice per unit 
price.  And, you'd probably wind up with a garage/warehouse full of 
transformers for many many years.

First off, while there are hundreds of folks on this list (and other 
places) building tesla coils,  there probably aren't hundreds willing to 
fork out a few hundred bucks for a purpose designed transformer, at least 
in any given year.  A lot of us are inveterate scroungers, and would rather 
wait a year until that pole transformer shows up surplus for $50.  There's 
also the shipping cost aspect.  A purpose built transformer might weigh 
over 100 pounds, and that ain't cheap to ship.  The shipping cost for used 
pole transformers is often more than the cost of the transformer.

Finally, I'll bet you couldn't get consensus on what characteristics this 
ultimate TC transformer should have.  Should it be 10 kVA or 5 kVA? Should 
it put out 10 kV, 15 kV, or 20 kV?... with NSTs, MOTs, and pole 
transformers, you sort of are forced into designs that make use of what you 
got... they only come in certain configurations (typically, arrived at over 
many decades of market forces...I'll bet the first Neon Sign transformers 
were a lot more customized, and a lot more expensive, than the standardized 
9,12,15 kV units at 10,15,30, 60 mA we get now.. Note that the voltages we 
get (9,12,15, 14.4 kV) are nice round number turn ratios... 75:1, 100:1, 
125:1, 120:1, etc... I don't think anybody optimized these things for 
performance.. no, they just said, what turns ratios should we use and 
picked some regular sequence.



I don't know.. I might be wrong. Maybe there's an untapped market niche 
here.. Maybe somebody has a few tens of thousands of dollars sitting around 
to invest? People have certainly invested in more speculative ventures.